1. Field of the Invention
The present invention relates to a semiconductor device and a method of fabricating the same, and more particularly, it relates to a semiconductor device having a structure in which a gate electrode is formed in a groove portion and a method of fabricating the same.
2. Description of the Background Art
A semiconductor device having a structure in which a gate electrode is formed in a groove portion is known in general.
The conventional semiconductor device comprises a groove portion formed on a main surface of a semiconductor substrate, a gate insulating film formed on a surface of the groove portion, and a gate electrode filling up the groove portion covered with the gate insulating film, wherein upper ends of the gate electrode, which are portions in contact with the gate insulating film, are each so formed as to have a height lower than the height of a surface of the semiconductor substrate. An oxide film having the same height as that of the surface of the semiconductor substrate is formed on an upper surface of the gate electrode. A screen oxide film is formed on the upper ends of the gate insulating film and the surfaces of the oxide film and the semiconductor substrate. The oxide film and the screen oxide film inhibit an impurity implanted through an ion implantation step from being directly implanted into the gate insulating film. Thus, the dielectric strength voltage of the gate insulating film can be inhibited from reduction.
In the conventional semiconductor device, however, the oxide film and the screen oxide film must be formed in order to inhibit the dielectric strength voltage of the gate insulating film from reduction. Consequently, a fabrication process is disadvantageously complicated.